{ INFORMATICS.MCCME.RU
  Problem statement: http://informatics.mccme.ru/moodle/mod/statements/view3.php?chapterid=438
  Verdict: Accepted
}
var a,b,c,x1,y1:extended;
begin
assign(input,'input.txt');
assign(output,'output.txt');
reset(input);
rewrite(output);
read(x1,y1,a,b,c);
write((abs(a*x1+b*y1+c)/sqrt(a*a+b*b)):0:5);
end.